Isolation of Brucella from Apparently Healthy Individuals

Abstract

In recent years the isolation of brucella organisms from cases of Hodgkin's disease 1 has caused considerable discussion. The confirmation of this finding in our laboratory and the statements in the literature that these organisms could be isolated from patients with various infections 2 led us to seek an explanation.

It seemed to us that the most likely explanation was that infection with brucella was widespread, at least in certain regions, and that the organism persisted in people furnishing favorable foci. In order to test this hypothesis it was decided to explore the possibility that tissues affording good conditions for growth of brucella organisms might actually harbor them. Since brucella are known to multiply in macrophages and fibroblasts, 3 it was thought that cultures of enlarged prostates and fibrosed fallopian tubes might reveal the presence of these organisms.

At present 34 prostates have been cultured. From these cultures Brucella abortus has been isolated in 2 instances and Brucella melitensis in a third. Forty-three fallopian tubes have been similarly studied. From one of these Brucella melitensis has been isolated. The cultures of the prostates and tubes were made by obtaining from the surgeon, in a sterile container, portions of the prostate which were removed through the urethra. The specimens were immediately macerated, extracted, and the tissue extract incubated in Bacto-tryptose Broth at 37.5°C in 10% C0₂ for 10 days. After 10 days the broth specimens were inoculated on Bacto-Tryptose Agar plates, and these were similarly incubated for 10 days. Unless positive specimens were obtained sooner, this procedure was repeated twice before discarding the specimens as negative. Identification of the organisms was made by 1) the morphology of the colony on tryptose agar, 2) the morphology and staining reactions of the individual organisms, 3) sugar reactions, and 4) agglutination with specific antiserum.